The state of all the CRTCs on an MST link must be recomputed, if DSC
gets enabled on any of the CRTCs on the link. For instance an MST
docking station's Panel Replay capability may depend on whether DSC is
enabled on any of the dock's streams (aka CRTCs). To assist the Panel
Replay state computation for a CRTC based on the above, track in the
CRTC state if DSC is enabled on any CRTC on an MST link.
The intel_link_bw_limits::force_fec_pipes mask is used for a reason
similar to the above: enable FEC on all CRTCs of a non-UHBR (8b10b) MST
link if DSC is enabled on any of the link's CRTCs. The FEC enabled state
for a CRTC doesn't indicate if DSC is enabled on a UHBR MST link (FEC is
always enabled by the HW for UHBR, hence it's not tracked by the
intel_crtc_state::fec_enable flag for such links, where this flag is
always false).
Based on the above, to be able to determine the DSC state on both
non-UHBR and UHBR MST links, track the more generic DSC-enabled-on-link
state (instead of the FEC-enabled-on-link state) for each CRTC in
intel_link_bw_limits.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20251015161934.262108-7-imre.deak@intel.com
Add support for forcing the link bpp on a connector via a connector
debugfs entry. During reducing link bpps due to a link BW limit, keep
bpps close to their forced value.
Add the debugfs entry to all relevant connectors: all DP connectors and
on an FDI link CRT/SDVO/LVDS/HDMI connectors.
v2:
- Move adding the debugfs entries to this patch.
- Rename i915_force_link_bpp to intel_force_link_bpp. (Jani)
- Select the relevant connectors via platform checks. (Jani)
- Use for_each_new_intel_connector_in_state(). (Jani)
- Fix 64 bit division vs. 32 bit build when converting str to q4. (lkp)
- Avoid division and addition overflow when converting str to q4.
v3:
- Add TODO: to make the non-DSC min bpp value connector specific. (Ankit)
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://lore.kernel.org/r/20250509180340.554867-12-imre.deak@intel.com
The system resume display mode restoration should happen with an output
configuration matching that of the suspend time saved mode. Since the
restored mode configuration is subject to the bpp fallback logic,
starting out with an unlimited bpp and reducing the bpp as required by
any (MST) link BW limit, the resulting bpp will match the one during
suspend only if the BW limit checks during suspend and resume are
applied in an identical way. The latter is not guaranteed at the moment,
since the pre-suspend MST topology may not be in place during resume
(for instance if the MST sink was disconnected while being suspended),
which makes the MST link BW check accept the unlimited bpp mode
configuration unconditionally without ensuring that the required BW fits
into the available MST link BW.
To fix the above, initialize the bpp fallback logic with the max link
bpp / force-FEC limits left behind by the suspend time mode save.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240220211841.448846-4-imre.deak@intel.com
At the moment modesetting a stream CRTC will fail if the stream's BW
along with the current BW of all the other streams on the same MST link
is above the total BW of the MST link. Make the BW sharing more dynamic
by trying to reduce the link bpp of one or more streams on the MST link
in this case.
When selecting a stream to reduce the BW for, take into account which
link segment in the MST topology ran out of BW and which streams go
through this link segment. For instance with A,B,C streams in the same
MST topology A and B may share the BW of a link segment downstream of a
branch device, stream C not downstream of the branch device, hence not
affecting this BW. If this link segment's BW runs out one or both of
stream A/B's BW will be reduced until their total BW is within limits.
While reducing the link bpp for a given stream DSC may need to be
enabled for it, which requires FEC on the whole MST link. Check for this
condition and recompute the state for all streams taking the FEC
overhead into account (on 8b/10b links).
v2:
- Rebase on s/min_bpp_pipes/min_bpp_reached_pipes/ change.
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030155843.2251023-29-imre.deak@intel.com
At the moment a modeset fails if the config computation of a pipe can't
fit its required BW to the available link BW even though the limitation
may be resolved by reducing the BW requirement of other pipes.
To improve the above this patch adds helper functions checking the
overall BW limits after all CRTC states have been computed. If the check
fails the maximum link bpp for a selected pipe will be reduced and all
the CRTC states will be recomputed until either the overall BW limit
check passes, or further bpp reduction is not possible (because all
pipes/encoders sharing the link BW reached their minimum link bpp).
Atm, the MST encoder allocates twice the required BW for YUV420 format
streams. A follow-up patchset will fix that, add a code comment about
this.
This change prepares for upcoming patches enabling the above BW
management on FDI and MST links.
v2:
- Rename intel_crtc_state::max_link_bpp to max_link_bpp_x16 and
intel_link_bw_limits::max_bpp to max_bpp_x16. (Jani)
v3:
- Add the helper functions in a separate patch. (Ville)
- Add the functions to intel_link_bw.c instead of intel_atomic.c (Ville)
- Return -ENOSPC instead of -EINVAL to userspace in case of a link BW
limit failure.
v4:
- Make intel_atomic_check_config() static.
v5: (Ville)
- Rename intel_link_bw_limits::min_bpp_pipes to min_bpp_reached_pipes
and intel_link_bw_reset_pipe_limit_to_min() to
intel_link_bw_set_min_bpp_for_pipe().
- Rename pipe_bpp to link_bpp in intel_link_bw_reduce_bpp().
- Add FIXME: comment about MST encoder's YUV420 BW allocation and
tracking the link bpp limit accordingly.
v6:
- Move intel_link_bw_compute_pipe_bpp() to intel_fdi.c (Ville)
- WARN_ON(BIT(pipe) & min_bpp_reached_pipes) in
intel_link_bw_set_bpp_limit_for_pipe(). (Ville)
- Rename intel_link_bw_set_min_bpp_for_pipe() to
intel_link_bw_set_bpp_limit_for_pipe() and
intel_link_bw_limits::min_bpp_reached_pipes to
bpp_limit_reached_pipes. (Ville)
- Remove unused header includes.
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230921195159.2646027-10-imre.deak@intel.com
